Canard airplanes are inherently more efficient and safer than airplanes with a horizontal tail. The canard lifts where the horizontal tail pushes down. Hence there is less lift induced drag in a canard airplane. A properly loaded canard airplane cannot stall or spin. Hence it is safer. Still, canard airplanes have never been very popular. Existing designs have compromises that limit their usefulness. The major compromises include a severely limited range of position for the center of gravity (CG) and high takeoff and landing speeds.
In the last couple decades, experimental aircraft builders have made significant improvements in the performance of small planes. Some of these deserve mention here because some of the innovations described in this application are extensions to their work. First, the major proponent of canard aircraft is Burt Rutan. His best known planes are the VARI-EZE (which spawned a whole family of canard aircraft) and the Voyager (which flew around the world without refueling). A good quality VARI-EZE typically reaches a top speed of 90 m/s with a 75 kW engine. Second, the most popular homebuilt planes in the world are the RV family, designed by Dick Van Grunsven. These are conventional airplanes with horizontal tails. A good quality RV typically reaches a top speed of 90 m/s with a 120 kW engine. Both these designs fly about twice as fast as a small Cessna (for example) using little, if any, more power. Thus they go about twice as far on any given amount of fuel.
Klaus Savier, Santa Paula, Calif., built the world's fastest VARI-EZE. He increased the power produced by the standard engine by about 30% (which should give a 9% speed increase to about 98 m/s) and has streamlined his VARI-EZE to reach top speeds of about 110 m/s and fuel economy of 21 km/I at 90 m/s. Dave Anders, Visalia, Calif., built the world's fastest RV-4. He boosted the power by 50% (which should give a 15% speed increase to 103 m/s) and has streamlined it to reach a speed of 122 m/s. The work of both these builders is well known within the experimental aircraft community.
Another airplane that deserves mention is the AR-5, which was designed from scratch by Mike Arnold. It is a conventional style airplane with outstanding aerodynamics. It is a one place airplane powered by an engine producing 49 kW. It flew 93 m/s in level flight and set a world record of 95 m/s for airplanes weighing under 300 kg in flight. (The official race rules allow some descent over the measured distance.) There are no plans or detailed information about this airplane. It has been studied carefully only by a few specialists at the invitation of the owner/builder. One known problem in the airplane is that the engine overheats with little provocation. Marginal cooling is one solution to the cooling drag problem. This might be acceptable for a single purpose airplane designed to break a speed record, but it is not acceptable in a general purpose aircraft.
One big disadvantage of the EZ family is the limited range of CG with which it can be flown safely. This results in the condition that, on the ground, the plane falls over backward when the pilot is not in it. The EZ airplanes are tricycle gear planes with the engine in the rear. If it falls over backward, it generally causes serious damage. The main disadvantage of the RV family is that they are conventional airplanes, hence can stall and spin if the speed is not high enough. Neither family of airplanes is designed to be as aerodynamic as desirable and the exceptional performance achieved by Klaus and Dave are the result of considerable investment of personal time and ingenuity.
Dr. Cliff Cordy built a Quickie II which flies over 80 m/s with a 45 kW engine. This is extremely fast for the power, despite the abominable engine cooling and wheel fairings that were part of the kit design. That means the wings and fuselage are extremely aerodynamic. The big disadvantage of the Q2 is that the canard is behind the engine, thus very heavily loaded. In order for the wing to be far enough forward to act as a wing, not a horizontal stabilizer, the distance from the wing to the canard must be small, and the CG of the airplane is very critical.
There is no prior single engine canard airplane that has a reasonably wide range of allowable CG position. The main difficulty in designing a single engine canard airplane is that the engine must be at the front or rear of the airplane, not on the wing, as is possible in a twin engine airplane. Placing the engine above the airplane is theoretically possible, but that introduces a whole set of undesirable mechanical and aerodynamic problems. In existing airplanes with the engine in front, as in the Quickie family, the canard has to carry the majority of the weight of the airplane. This forces the canard to be large, and it almost becomes the wing. To keep the wing far enough forward to function as a wing instead of a horizontal stabilizer, the distance from the wing to the canard must be small. This results in an undesirably critical location of the CG. If the engine is in the rear, as in the EZ family, and in the original incarnation of the race airplane named Pushy Galore, the wing carries most of the weight, but the pusher configuration introduces a new set of limitations, including the impossibility of making a taildragger configuration (with a small tail wheel as opposed to a nose wheel) and less efficient engine cooling.
No existing canard airplane that is designed to fly fast provides the ability to fly and land at low speeds. In conventional aircraft, slow flight is achieved by using wing flaps. In a canard design, the use of wing flaps would actually increase the minimum flying speed.